Patent GB-886395-A (GB)
Title: Improvements relating to automatic displacement control mechanism
Inventor: LEMAY CHRISTOPHER ARCHIBALD GO
IPC: G05B19/4105
Filed: 1957-03-29
Abstract: 886,395. Electric analogue computers. ELECTRIC & MUSICAL INDUSTRIES Ltd. March 29, 1958 [March 25, 1957 ; March 29, 1957], No. 10450/57 and 10452/57. Class 37. [Also in Group XXXVIII] Apparatus for automatically controlling a cutting-tool, e.g. an oxygen burner, in response to a programme comprises at least one interpolator interpolating with respect to a parameter # and provides an output representing co-ordinates on the required cutting locus, the rate of change of the parameter # being varied so that the square of the actual velocity of the burner (ds/dt)<SP>2</SP> is maintained equal to the square of the required burner velocity (k<SP>2</SP>) (see Group XXXVIII). Interpolators (Fig. 4).-The interpolator 21 comprises two " parabolic " bridges PB1, PB2, the former comprising a " linear " and a " quadratic " transformer T6, T7 interconnected as in Specification 796,994, PB2 being similar and comprising transformers T8, T9. The output contacts S1a to S13a and S1b to S13b of bridge PB1 are connected in pairs as are those of PB2. Shaft 25 (Fig. 1) carries a selector for the contacts having four mechanically connected electrically insulated brushes connected to opposite ends of tapped autotransformers T10, T11, respectively, the tappings being connected to the contacts 29 which are traversed by selector 9 on shaft 26. Input leads U1, U3 and U4, U6 of bridges PB1, PB2 are connected to the selectors of stepping switches SWC, SWD, respectively, which are alternately advanced by feeding stepping mechanisms SWCM, SWDM with pulses from 31 through commutator 31a driven by shaft 26. Input leads U2, U5 are connected to output terminals X20, X40 of stores X2, X4 (Fig. 1). The voltages on the output contacts representing close values of # in accordance with Specification 796,994 are applied alternately across transformers T10, T11 by brushes and linear sub-interpolation of the output voltages of the bridges is achieved in conjunction with contacts 29, and selector 9. The operation of the interpolator is as follows : signals are applied to the interpolator representing x 0 , and as shaft 26 is rotated brushes move downwards over bridge PB1 and signals x 1 , x 2  are set up in stores X4, X5 (Fig. 1), respectively, and applied to input leads U5, U6 of bridge PB2. As brushes pass from bridge PB1 to PB2 the output of the interpolator starts to vary to give values of x for points on curve x=f(6) (Fig. 5b) for the interval # 2  to # 2 . During this time signals representing x 3 , x 4  are set up in stores X1, X2 (Fig. 1), respectively, so that before traverse of bridge PB2 is completed signals representing x 2 , x 3 , x 4  are applied to input leads U1, U2, U3 of bridge PB1. The operation of the y-interpolator 22 (Fig. 1) is similar and simultaneous. The flux variation of subinterpolating transformers T10, T11 may be used to compensate for cutter " radius " in accordance with Specification 830,461. The interpolator 21 may be modified as shown in Fig. 7 to smooth out changes in slope ds/d# by the   connection of contact S14a of input lead U4 through four transformer sections 65-68 wound on cores of transformers T8, T7, T6 and T9, respectively, the theory being fully explained with reference to Fig. 8, not shown. Specifications 802,472, 830,462, 846,381, 847,367, 849,091, 863,114 and 882,549 also are referred to.